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United States Patent |
6,002,343
|
Auerbach
,   et al.
|
December 14, 1999
|
Changing Indicia in an electronic tag when tampered with
Abstract
An electronic seal including an electronic tag, an electrically resistive
element in electrical communication with and attached to the tag, the
resistive element being bondable to an object so as to define an
electrical resistance, wherein a change in bonding of the element to the
object causes a change in the electrical resistance, the change in
electrical resistance being communicated to the tag.
Inventors:
|
Auerbach; Micha (Maccabim, IL);
Cohen; Rony (Zoran, IL);
Leibman; Vadim (Migdal Haemek, IL);
Genin; Arcadi (Bat Yam, IL);
Ilyaev; Reuven (Tel Aviv, IL)
|
Assignee:
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Hi-G-Tek Ltd. (Or Yehuda, IL)
|
Appl. No.:
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815389 |
Filed:
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March 11, 1997 |
Foreign Application Priority Data
Current U.S. Class: |
340/10.41; 340/5.33; 340/572.1; 340/572.8; 340/664; 340/825.78 |
Intern'l Class: |
H04Q 001/00 |
Field of Search: |
340/825.78,825.34,825.54,572.1,572.2,561,664
|
References Cited
U.S. Patent Documents
4218674 | Aug., 1980 | Brosow | 340/825.
|
4827395 | May., 1989 | Anders | 340/825.
|
4952913 | Aug., 1990 | Pauley et al. | 340/573.
|
5072213 | Dec., 1991 | Close | 340/572.
|
5097253 | Mar., 1992 | Eschbach | 340/545.
|
5099228 | Mar., 1992 | Israel et al. | 340/572.
|
5266925 | Nov., 1993 | Uercellotti et al. | 340/572.
|
5656996 | Aug., 1997 | Houser | 340/568.
|
Foreign Patent Documents |
0513456 | Nov., 1992 | EP.
| |
07 02 324 | Mar., 1996 | EP | .
|
2256958 | Dec., 1992 | GB.
| |
2276025 | Sep., 1994 | GB | .
|
2279170 | Dec., 1994 | GB | .
|
WO 90/09648 | Aug., 1990 | WO | .
|
WO 94/28523 | Dec., 1994 | WO | .
|
WO 95/14938 | Jun., 1995 | WO | .
|
WO 95/29456 | Nov., 1995 | WO | .
|
WO 96/07938 | Mar., 1996 | WO | .
|
WO 96/16387 | May., 1996 | WO | .
|
WO 96/20463 | Jul., 1996 | WO.
| |
WO 97/38364 | Oct., 1997 | WO.
| |
Primary Examiner: Zimmerman; Brian
Attorney, Agent or Firm: Koundakjian; Stephen J.
Claims
We claim:
1. An electronic seal comprising:
an electronic tag;
an electrically resistive element in electrical communication with and
attached to said tag, wherein tampering with the electrically resistive
element causes a change in said electrical resistance, said change in
electrical resistance being communicated to said tag, wherein said
resistive element comprises a multiplicity of resistive wires, wherein
only a random number of said wires are electrically connected to internal
connection points in said tag such that said resistive element has a
statistically random electrical resistance.
2. A seal according to claim 1 wherein said tag transmits said change in
electrical resistance to a transceiver, said transceiver communicating
said change to a detection system.
3. A seal according to claim 2 wherein said tag transmits said change to
said transceiver by RF transmission.
4. A seal according to claim 1 wherein said resistive element is bonded to
said tag with an electrically conductive adhesive having an adhesive
strength, said element being bonded to said object with an adhesive
strength greater than the adhesive strength of said conductive adhesive.
5. A seal according to claim 1 wherein said tag operates in a sleeping mode
and said change in electrical resistance is communicated to said tag only
when said tag is activated with a wake-up signal.
6. A seal according to claim 5 wherein a transceiver communicates said
wake-up signal to said tag.
7. A seal according to claim 1 and wherein said tag comprises a timer and
memory for monitoring time and duration of said change in electrical
resistance.
8. A seal according to claim 7 and wherein said memory stores at least one
of identification data and asset data.
9. An electronic seal comprising:
an electronic tag;
an electrically resistive element in electrical communication with and
attached to said tag, said resistive element being adhesively bondable to
an object so as to define an electrical resistance, wherein a change in
adhesive bonding of said element to said object causes a change in said
electrical resistance, said change in electrical resistance being
communicated to said tag, wherein said resistive element is bonded to said
tag with an electrically conductive adhesive having an adhesive strength,
said element being bonded to said object with an adhesive strength greater
than the adhesive strength of said conductive adhesive.
Description
FIELD OF THE INVENTION
The present invention relates to electronic seals generally, and
particularly to RF-interrogated identification tags and electronic seals.
BACKGROUND OF THE INVENTION
It is well known to identify objects with tags that can be monitored,
sensed or interrogated from a remote location.
There are several types of RF-interrogated identification tags currently on
the market. One example is the SMART Pass system developed by AMTECH Corp.
of Dallas, Tex. Their system uses passive RF tags, a little larger than a
standard credit card and nearly 1/2 an inch thick. The tags require a
large, high-frequency antenna capable of sending a microwave-frequency RF
pulse strong enough to energize the tag to the point where it can return
its identification number. The maximum range of the AMTECH system is a few
meters. The AMTECH system antenna is designed to be mounted on a metal
pole. Its size (38.1 cm.times.41.7 cm.times.10.2 cm) and power
requirements, are prohibitive for use in an office or hospital environment
for tracking capital assets. The system does not allow tracking several
objects simultaneously.
Other identification tag systems, such as Texas Instrument's TIRIS system,
the Dutch NEDAP monitoring system, and the Israeli On-Track Innovations
PorTrac system, are all distance limited solutions for remote,
contactless, control of tags and objects. The practical reliable
communication distance between tag and object is about 10 cm. Larger
distances require very strong magnetic fields, utilizing large and costly
hardware associated with them.
Currently available active or passive electronic tagging systems either
require a large and costly portable monitoring antenna with limited
interrogation range (several score centimeters), or a physical connection
to the electronic tag.
SUMMARY OF THE INVENTION
The present invention seeks to provide improved, battery operated, active
electronic RF tags that can communicate with a small transceiver over
distances of up to few score meters. The system of the present invention
allows a user to read many tags at the same time, with a lifetime of
several years for each tag.
In a preferred embodiment of the present invention, a very low power
receiver and a transmitter are integrated on one silicon chip, thereby
achieving a significant miniaturization of the tag with a long life time,
and at the same time offering a significant reduction in unit price,
despite requiring the use of a battery. The use of a backup battery helps
overcome the range problem, the high cost of the reader, and the
environmental problems associated with the emission of very strong
magnetic fields.
The tag includes a resistive element disposed between the tag body and the
object enclosure. Any attempt to remove the tag from the object, will
cause an irreversible damage/change to the resistor layer between the tag
and the object, resulting in an electronic indication/alarm signal.
The electronic tag is a battery operated device and has a unique 64 bits
serial number. The tag transmits its data upon receiving a wake up signal
from a transceiver. The transceiver can initiate a search signal
automatically, in pre-defined time intervals, or upon initiation of a
signal from a main network computer. The transceivers can be connected
together through any kind of LAN system.
After attaching the tag to an object, any attempt to remove the tag from
the object will cause a change in the unique code, i.e., resistance
associated with the resistive element of the tag. The tag functions both
as an identification tag and as an electronic seal.
The electronic seal of the present invention operates with a battery in a
sleeping mode of operation, and activates its receiver circuitry only once
about every 1.5 sec for a duration of about 10 ms. The measuring and
transmitter circuitry is activated only when a wake-up signal is received
from the transceiver. In this way an operating range of up to 30 meters
may be achieved with a life time of a few years, depending on the number
of interrogations per day. The battery may consume less than 10
microamperes of current during sleeping mode.
The transceiver emits a wake-up signal with a duration of more than 1.5
Sec. to ensure reception of all tags in a given area. The tags respond
with a random delay, within the required time interval. The system of the
present invention can detect and control up to 50 tags in one location
with a search time of 2 sec maximum.
There is thus provided in accordance with a preferred embodiment of the
present invention, an electronic seal including, an electronic tag, an
electrically resistive element in electrical communication with and
attached to the tag, the resistive element being bondable to an object so
as to define an electrical resistance, wherein a change in bonding of the
element to the object causes a change in the electrical resistance, the
change in electrical resistance being communicated to the tag.
In accordance with a preferred embodiment of the present invention, the tag
transmits the change in electrical resistance to a transceiver, the
transceiver communicating the change to a detection system. Preferably the
tag transmits the change to the transmitter by RF transmission.
In accordance with one preferred embodiment of the present invention, the
resistive element comprises a resistive ink applied to a flexible
material.
In accordance with another preferred embodiment of the present invention,
the resistive element comprises a multiplicity of resistive wires, wherein
only a random number of the wires are electrically connected to the tag.
Additionally in accordance with a preferred embodiment of the present
invention, the resistive element is bonded to the tag with an electrically
conductive adhesive having an adhesive strength, the element being bonded
to the object with an adhesive strength greater than the adhesive strength
of the conductive adhesive.
Further in accordance with a preferred embodiment of the present invention,
the tag operates in a sleeping mode and the change in electrical
resistance is communicated to the tag only when the tag is activated with
a wake-up signal. Preferably a transceiver communicates the wake-up signal
to the tag.
In accordance with a preferred embodiment of the present invention, the tag
includes a timer and memory for monitoring time and duration of the change
in electrical resistance. Preferably the memory stores at least one of
identification data and asset data.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from
the following detailed description, taken in conjunction with the drawings
in which:
FIG. 1 is a simplified pictorial illustration of an electronic seal,
including an electronic tag and an electrically resistive element,
constructed and operative in accordance with a preferred embodiment of the
present invention;
FIG. 2 is a simplified sectional illustration of the electronic seal of
FIG. 1, taken along lines II--II in FIG. 1;
FIG. 3 is a simplified sectional illustration of the resistive element of
FIG. 1, taken along lines III--III in FIG. 2;
FIG. 4 is a simplified pictorial cutaway illustration of an electronic
seal, including an electronic tag and an electrically resistive element,
constructed and operative in accordance with another preferred embodiment
of the present invention; and
FIG. 5 is a simplified block diagram of the electronic seals of FIGS. 1 and
4 used in a detection system, constructed and operative in accordance with
a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Reference is now made to FIGS. 1 and 2 which illustrate an electronic seal
10 constructed and operative in accordance with a preferred embodiment of
the present invention.
Electronic seal 10 includes an electronic tag 12 which preferably includes
electronics comprising a battery 14, a receiver antenna 16, receiver
circuitry 18, a transmitter antenna 20, transmitter circuitry 22, a
microprocessor 24, a timer 26, a logic and memory component 28, an
analog-to-digital (A/D) converter 30 and a current source 32. The
electronics of tag 12 is not limited to the abovementioned components, and
may include more or less components, depending upon the application.
The electronics of tag 12 are in electrical communication with an
electrically resistive element 34, such as via I/O pads 36. Resistive
element 34 is preferably bonded to an object 40 with an adhesive 42 so as
to define an electrical resistance. Any change in bonding of element 34 to
object 40 causes a change in the electrical resistance. Adhesive 42 may be
a double sided adhesive tape or adhesive foam.
The resistive element of the present invention may be constructed in a
variety of manners. Reference is now made to FIG. 3 which illustrates
resistive element 34, constructed and operative in accordance with one
embodiment of the present invention. A resistive ink 44, preferably
polymer based, is applied to a flexible material 46, such as polyester or
polyimide films, e.g., MYLAR or KAPTON. Resistive ink 44 may be applied in
a variety of manners, e.g., screen printing, roller coating, dipping,
transfer deposition, or any other process that provides a controlled
coating. Resistive ink 44 is printed on material 46 in any suitable
pattern to provide a desired resistance value which may be adjusted after
curing by laser trimming, abrasion or mechanical punching, for example.
Preferably I/O pads 48 are connected to the pattern of resistive ink 44,
pads 48 being in electrical communication with I/O pads 36 of tag 12.
Resistive element 34 is preferably attached to tag 12 by means of a
conductive adhesive 50, such as a metal impregnated adhesive. Preferably
the adhesive strength of adhesive 42 is greater than the adhesive strength
of conductive adhesive 50, so that removal of tag 12 from object 40 causes
shearing or other deformation of conductive adhesive 50, and alters the
resistance of resistive element 34. Alteration of the resistance of
element 34 may be stored in memory component 28 and/or may be transmitted
via transmitter 22 and antenna 20 to a detection system (not shown).
Reference is now made to FIG. 4 which illustrates an electronic seal 60,
constructed and operative in accordance with another preferred embodiment
of the present invention. Electronic seal 60 includes a tag 62 which
preferably includes electronics substantially identical to electronics of
tag 12 of seal 10. Electronic seal 60 includes a resistive element 64
which comprises a multiplicity of resistive wires 66, preferably
constructed of a high resistivity material such as nickel chrome. Each
wire 66 is insulated from each other and from the external world. Wires 66
are attached to internal I/O pins 68 of tag 62, such as by crimping or
soldering, wherein only a random number of wires 66 are electrically
connected to pins 68 and the remainder of wires 66 are not connected to
pins 68. The random connection results in a statistically random
electrical resistance of resistive element 64, which resistance cannot be
measured from the outside of tag 62.
Seal 60 may be potted for added protection from the environment. Seal 60 is
preferably attached to an object (not shown) in a manner substantially
similar to seal 10, as described hereinabove. Removal of tag 62 from the
object causes shearing or other deformation of wires 66, and alters the
resistance of resistive element 64. Alteration of the resistance of
element 64 may be stored in memory component 28 (not shown in FIG. 4)
and/or may be transmitted via transmitter 22 and antenna 20 to a detection
system (all not shown in FIG. 4).
Reference is now made to FIG. 5 which illustrates a simplified block
diagram of the electronic seals of FIGS. 1 and 4 used in a detection
system 70, constructed and operative in accordance with a preferred
embodiment of the present invention.
Detection system 70 preferably includes a transceiver 72 which communicates
with either tag 12 or 62 via an RF transmitter 74 and an RF receiver 76.
Transceiver 72 preferably also communicates with monitoring apparatus 78
and/or alarm apparatus 80, via wired or wireless communication, such as a
LAN.
Preferably tag 12 or 62 operates in a sleeping mode so as to conserve
energy of battery 14. Tag 12 or 62 is activated only upon receipt of a
wake-up signal from transceiver 72. Once tag 12 or 62 is activated, any
change in electrical resistance of resistive element 34 or 64,
respectively, is communicated or monitored. For example, the change in
resistance may be stored in memory component 28 and/or relayed to
transceiver 72 and thence to either monitoring apparatus 78 or alarm
apparatus 80. Timer 26 and/or memory component 28 may be used to monitor
time and duration of the change in electrical resistance.
Preferably memory component 28 stores at least one of identification data
and asset data. Transceiver 72 may interrogate tag 12 or 62 for the
identification and/or asset data. The asset data may include a variety of
information about the object being monitored, including inventory and
sub-inventory information.
It is appreciated that various features of the invention which are, for
clarity, described in the contexts of separate embodiments may also be
provided in combination in a single embodiment. Conversely, various
features of the invention which are, for brevity, described in the context
of a single embodiment may also be provided separately or in any suitable
subcombination.
It will be appreciated by persons skilled in the art that the present
invention is not limited by what has been particularly shown and described
hereinabove. Rather the scope of the present invention is defined only by
the claims which follow:
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